Rheological properties of mucilage extracted from Alyssum homolocarpum seed as a new source of thickening agent

The rheological properties of Alyssum homolocarpum seed mucilage as influences of gum concentrations (1.5%, 2%, 2.5%, 3%, 3.5% and 4%) and temperatures (5, 25, 45, and 65 degrees C) were investigated. Effects of pH (3-9), salts concentrations (CaCl2 and MgCl2 from 0 to 0.049 M: NaCl and KCl from 0 to 0.17 M) and Sucrose Concentration (0% to 40%) were also evaluated at 3% weight/weight (w/w) of A. homolocarpum seed gum. The power law model well described the theological behavior of the A. homolocarpum seed mucilage solutions with high determination coefficients, R-2. The gum exhibited non-Newtonian, pseudoplastic behavior at all temperatures and concentrations. An increase in concentration, decreased the flow behavior indices, n, and increased the consistency coefficients; k. Increasing temperature decreased the viscosity and pseudoplasticity. The temperature effect was described using Arrhenius equation and as the activation energy (E-a) decreased the gum concentration increased. The apparent viscosity varied according to variation in pH, the highest viscosity was obtained at pH of 9 and the lowest at pH of 3, nevertheless there were no significant difference between pH ranging from five to nine. The apparent viscosity decreased with addition of Na+, K+, Ca2+ (< 0.01 M) and Mg2+ (< 0.039 M), whereas it increased with the addition of Ca2+ and Mg2+ at concentration higher than 0.01 M and 0.039 M, respectively. An increase in concentration was accompanied with an increase in pseudoplasticity (increase in k and decrease in n). (c) 2008 Elsevier Ltd. All rights reserved.